Iron-based catalysts, their preparation methods and applications

Abstract

This invention relates to the field of catalyst technology, and discloses an iron-based catalyst, its preparation method, and its application. The catalyst has the structure shown in the following formula: FeA a M b Q c O x Wherein, A is Cu and / or Zr; M is selected from at least one Group IIA metal element; Q is selected from at least one lanthanide element; a, b, and c are the molar ratios of A, M, and Q to Fe, respectively, where a = 0.1–0.6; b = 0.1–0.4; c = 0.05–0.2; and x is the total number of oxygen atoms required to satisfy the valence of each element in the active component. The iron-based catalyst, through the specific combination of active metal components and their contents, exhibits high CO conversion rate and low-carbon olefin selectivity.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to an iron-based catalyst, its preparation method, and its application. Background Technology

[0002] Syngas's main components are CO and H2. Converting syngas into olefins can solve the pollution generated during coal combustion and improve energy efficiency. There are direct and indirect methods for converting syngas into olefins. The indirect method generally follows a route from syngas to methanol and then to low-carbon olefins, while the Fischer-Tropsch process is one of the most efficient routes for synthesizing olefins from syngas in one step.

[0003] CN106311317A discloses a catalyst and a method for the one-step direct preparation of low-carbon olefins from syngas. The catalyst is a composite material consisting of a multi-component metal complex and a hierarchical porous inorganic solid acid. However, when this catalyst is used to synthesize low-carbon olefins, it suffers from problems such as low CO single-pass conversion, a wide distribution of reaction products, and low selectivity for low-carbon olefins. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems of low carbon monoxide conversion rate and low selectivity of low-carbon olefins in the reaction of syngas to low-carbon olefins in the prior art, and to provide an iron-based catalyst, its preparation method and application. The iron-based catalyst has high CO conversion rate and low-carbon olefin selectivity through the combination of specific active metal components and contents.

[0005] To achieve the above objectives, a first aspect of the present invention provides an iron-based catalyst, wherein the catalyst has a structure as shown in the following formula: FeA a M b Q c O x ;

[0006] Wherein, A is Cu and / or Zr; M is selected from at least one of Group IIA metals; Q is selected from at least one of lanthanides.

[0007] a, b, and c are the molar ratios of A, M, and Q to Fe, respectively, where a = 0.1-0.6; b = 0.1-0.4; c = 0.05-0.2; and x is the total number of oxygen atoms required to satisfy the valence of each element in the active component.

[0008] A second aspect of the present invention provides a method for preparing an iron-based catalyst, wherein the method comprises:

[0009] (1) Prepare a mixed solution containing Fe source, A source, M source, Q source and structure modifier;

[0010] (2) The mixed solution was subjected to hydrothermal treatment, and the resulting solid product was dried and calcined to obtain an iron-based catalyst.

[0011] Wherein, A is Cu and / or Zr; M is selected from at least one of Group IIA metals; and Q is selected from at least one of the lanthanides.

[0012] The third aspect of this invention provides an iron-based catalyst prepared by the preparation method described in the second aspect.

[0013] The fourth aspect of this invention provides the application of the iron-based catalyst described in the first or third aspect in the conversion of syngas into low-carbon olefins.

[0014] The beneficial effects achieved through the above technical solution are as follows:

[0015] The iron-based catalyst provided by this invention, through the combination of specific types and contents of active metals and the addition of structure modifiers during the preparation process, makes the catalyst particles less prone to agglomeration during the preparation process, thereby improving the conversion rate and selectivity for low-carbon olefins. Detailed Implementation

[0016] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0017] The first aspect of this invention provides an iron-based catalyst having the structure shown in the following formula: FeA a M b Q c O x ;

[0018] Wherein, A is Cu and / or Zr; M is selected from at least one of Group IIA metals; Q is selected from at least one of lanthanides.

[0019] a, b, and c are the molar ratios of A, M, and Q to Fe, respectively, where a = 0.1-0.6; b = 0.1-0.4; c = 0.05-0.2; and x is the total number of oxygen atoms required to satisfy the valence of each element in the active component.

[0020] In this invention, the iron-based catalyst having the above-mentioned composition, through the coordination of the components, can improve the catalytic activity of the iron-based catalyst, and increase the conversion rate and selectivity for low-carbon olefins.

[0021] It should be noted that in this invention, "FeA" a Mb Q c O x The general formula "" only represents the individual elements and their molar content of the active component in the catalyst, and does not mean that the active component of the catalyst in this invention exists as a molecule of this general formula.

[0022] According to the present invention, preferably, a = 0.2-0.5.

[0023] According to the present invention, preferably, M is Mg and / or Sr.

[0024] According to the present invention, preferably, b = 0.1-0.35.

[0025] According to the present invention, preferably, Q is Nd and / or Sm.

[0026] According to the present invention, preferably, c = 0.05-0.15.

[0027] In this invention, the iron-based catalyst has the above-mentioned preferred elemental composition and content combination, has multiple active sites, and high catalytic activity. When used in syngas conversion reaction, it has higher CO conversion rate and higher selectivity for low-carbon olefins.

[0028] In this invention, the elemental composition and content of the iron-based catalyst are calculated by the feeding ratio during the preparation process.

[0029] According to the present invention, preferably, the particle size of the catalyst is 200-900 nm, for example, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 850 nm, 900 nm, or any range between the two, preferably 250-500 nm. In the present invention, the finer particle size of the catalyst provides more active sites, resulting in higher conversion rates and higher selectivity for low-carbon olefins in the syngas conversion reaction.

[0030] In this invention, the particle size of the catalyst was measured using a ZETASIZER Nano-ZS laser nanoparticle size analyzer from Malvern Instruments Ltd.

[0031] A second aspect of the present invention provides a method for preparing an iron-based catalyst, wherein the method comprises:

[0032] (1) Prepare a mixed solution containing Fe source, A source, M source, Q source and structure modifier;

[0033] (2) The mixed solution was subjected to hydrothermal treatment, and the resulting solid product was dried and calcined to obtain an iron-based catalyst.

[0034] Wherein, A is Cu and / or Zr; M is selected from at least one of Group IIA metals; and Q is selected from at least one of the lanthanides.

[0035] In this invention, a catalyst is prepared by adding a structure modifier and performing hydrothermal treatment. During the preparation process, the catalyst particles are less prone to agglomeration and are finer, which can improve the conversion rate and selectivity of low-carbon olefins in the syngas conversion reaction.

[0036] According to the present invention, the type of Fe source is not particularly limited, and any soluble iron salt is acceptable. Preferably, the Fe source is selected from at least one of ferric nitrate, ferric chloride, and ferric sulfate.

[0037] According to the present invention, the types of the A source, M source, and Q source are not particularly limited, and any soluble salt is acceptable. Preferably, the A source, M source, and Q source are each independently a nitrate and / or a chloride.

[0038] According to the present invention, preferably, M is Mg and / or Sr.

[0039] According to the present invention, preferably, Q is Nd and / or Sm.

[0040] According to the present invention, preferably, in the mixed solution, the molar amount of Fe source is calculated as Fe, the molar amount of A source is calculated as A, and the molar ratio of Fe source to A source is 1:0.1-0.6, for example, 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, or any range between the two, preferably 1:0.2-0.5.

[0041] According to the present invention, preferably, the molar amount of Fe source is calculated as Fe, the molar amount of M source is calculated as M, and the molar ratio of Fe source to M source is 1:0.1-0.4, for example 1:0.1, 1:0.15, 1:0.2, 1:0.25, 1:0.3, 1:0.35, 1:0.4, or any range between the two, preferably 1:0.1-0.35.

[0042] According to the present invention, preferably, the molar amount of Fe source is calculated as Fe, the molar amount of Q source is calculated as Q, and the molar ratio of Fe source to Q source is 1:0.05-0.2, for example, 1:0.05, 1:0.1, 1:0.15, 1:0.2, or any range between the two, preferably 1:0.05-0.15.

[0043] In this invention, preferably, the catalyst further contains the element O.

[0044] According to the present invention, preferably, the O element content is the total number of oxygen atoms required to satisfy the valence of each element in the active component.

[0045] According to the present invention, the structure modifier is an auxiliary agent capable of improving the dispersibility of catalyst particles. Preferably, the structure modifier is a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer and / or ammonium polyacrylate. In the present invention, the use of the above-mentioned structure modifier in the preparation of the catalyst can improve the dispersion of catalyst particles during the preparation process, resulting in finer catalyst particles with better conversion rate and better selectivity for low-carbon olefins when used in syngas reforming reactions.

[0046] According to the present invention, preferably, the structure modifier is a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer and ammonium polyacrylate.

[0047] According to the present invention, preferably, the mass ratio of the polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer to ammonium polyacrylate is 0.5-5:1, for example, 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, or any range between the two, preferably 1-4:1. In the present invention, the catalyst prepared using the above-mentioned mass ratio of structure modifier can be adsorbed on the particle surface, effectively inhibiting particle aggregation and obtaining good dispersibility.

[0048] In this invention, preferably, the weight-average molecular weight of the polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer is 5000-7000; and the weight-average molecular weight of the ammonium polyacrylate is 4000-6000.

[0049] According to the present invention, preferably, the amount of the structure modifier added is 30-60 wt% of the total weight of the catalyst, preferably 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, or any range between the two, preferably 35-55 wt%.

[0050] According to a preferred embodiment of the present invention, the preparation process of the mixed solution in step (1) includes: preparing a mixed solution I containing Fe source, A source, M source and Q source, and then preparing an aqueous solution of structure modifier and mixing it with mixed solution I to obtain mixed solution II.

[0051] According to the present invention, preferably, the conditions for the hydrothermal treatment include: a reaction temperature of 120-260°C, for example, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, or any range between the two, preferably 140-240°C; and a reaction time of 12-60 hours, for example, 12 hours, 14 hours, 16 hours, 18 hours, 20 hours, 24 hours, 28 hours, 32 hours, 36 hours, 40 hours, 44 hours, 48 ​​hours, 54 hours, 56 hours, 60 hours, or any range between the two, preferably 18-54 hours. In the present invention, hydrothermal treatment under the above conditions can result in a more uniform particle size distribution.

[0052] In this invention, the equipment used for the hydrothermal treatment is not particularly limited, and those skilled in the art can make appropriate selections. Preferably, the hydrothermal treatment is carried out in a reaction vessel.

[0053] In this invention, after the hydrothermal treatment is completed, the reactor is cooled to room temperature to facilitate subsequent steps and avoid safety hazards caused by opening the reactor at high temperatures.

[0054] In this invention, preferably, the hydrothermal treatment further includes steps of aging, filtering, washing, and drying the product. The aging conditions are not particularly limited, and those skilled in the art can choose conventional aging conditions. Preferably, the aging conditions include: aging at room temperature for 2-12 hours.

[0055] In this invention, there is no particular limitation on the separation method of aged products. For example, conventional separation methods in the art, such as filtration, vacuum filtration, and centrifugation, can all achieve the purpose of this invention.

[0056] In this invention, the washing method is a conventional washing method in the art, and there are no particular limitations on the washing method and washing solvent. Preferably, deionized water and ethanol can be used to wash the aged products.

[0057] In this invention, the drying conditions are not particularly limited. According to a preferred embodiment of the invention, the drying is carried out under vacuum at a temperature of 50-100°C. The reaction time can be adjusted reasonably according to actual needs; preferably, the drying time is 12-48 hours. Drying under vacuum allows for more thorough removal of the washing solvent.

[0058] According to the present invention, preferably, the calcination conditions include: a calcination temperature of 400-600℃, more preferably 450-550℃; and a calcination time of 3-36 hours, more preferably 6-30 hours.

[0059] The third aspect of this invention provides an iron-based catalyst prepared by the preparation method described in the second aspect.

[0060] The fourth aspect of this invention provides the application of the iron-based catalyst described in the first or third aspect in the conversion of syngas into low-carbon olefins.

[0061] In this invention, a method for directly producing low-carbon olefins from syngas includes: using syngas as a raw material, and reacting the raw material with the iron-based catalyst to generate low-carbon olefins.

[0062] In this invention, the term "low-carbon olefin" has the conventional meaning in the art, referring to C2-C4 hydrocarbons containing carbon-carbon double bonds.

[0063] According to the present invention, preferably, the conditions for the syngas conversion reaction include: the syngas comprising CO and H2; a reaction temperature of 280-400°C; a reaction pressure of atmospheric pressure to 8 MPa; an H2 / CO molar ratio of 1-5:1; and a catalyst loading of 500-12000 h⁻¹. -1 .

[0064] Before the catalyst of this invention is used in the direct production of low-carbon olefins from syngas, it preferably undergoes an online reduction process. Specific reduction conditions can be reasonably selected by those skilled in the art without requiring inventive effort. For example, but not limited to, reduction conditions include:

[0065] The reduction temperature is 350-600℃;

[0066] The reducing agent is H2 and / or CO;

[0067] The reduction pressure is atmospheric pressure - 2 MPa (gauge pressure);

[0068] The volume hourly space velocity of the reducing agent is 2000-9000 h⁻¹ -1 ;

[0069] The restoration time is 12-60 hours.

[0070] According to a particularly preferred embodiment of the present invention, a method for preparing an iron-based catalyst, the method comprising:

[0071] (1) Prepare a mixed solution containing Fe source, A source, M source, Q source and structure modifier;

[0072] (2) The mixed solution was subjected to hydrothermal treatment, and the resulting solid product was dried and calcined to obtain an iron-based catalyst.

[0073] Wherein, A is Cu and / or Zr; M is Mg and / or Sr; Q is Nd and / or Sm;

[0074] In the mixed solution, the molar amount of Fe source is calculated as Fe, the molar amount of A source is calculated as A, and the molar ratio of Fe source to A source is 1:0.2-0.5.

[0075] The molar amount of Fe source is expressed as Fe, the molar amount of M source is expressed as M, and the molar ratio of Fe source to M source is 1:0.1-0.35.

[0076] The molar amount of Fe source is expressed as Fe, the molar amount of Q source is expressed as Q, and the molar ratio of Fe source to Q source is 1:0.05-0.15.

[0077] The structure modifier is a triblock copolymer of polyethylene oxide-polypropylene oxide-polyethylene oxide and ammonium polyacrylate;

[0078] The amount of the structure modifier added is 35-55 wt% of the total weight of the catalyst.

[0079] The present invention will be described in detail below through examples and comparative examples. Unless otherwise specified, all reagents used in the following examples and comparative examples are commercially available.

[0080] The weight-average molecular weight of ammonium polyacrylate is 5000;

[0081] The weight-average molecular weight of the polyethylene oxide-propylene oxide-ethylene oxide triblock copolymer is 5800.

[0082] Example 1

[0083] Ferric nitrate nonahydrate (Fe(NO3)3·9H2O) containing 0.1 mol Fe, copper nitrate trihydrate (Cu(NO3)2·3H2O) containing 0.04 mol Cu, magnesium nitrate hexahydrate (Mg(NO3)2·6H2O) containing 0.025 mol Mg, and neodymium nitrate hexahydrate (Nd(NO3)3·6H2O) containing 0.01 mol Nd were sequentially dissolved in 100 mL of deionized water. After complete dissolution, mixture I was obtained. 4.8 g of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (P123) and 1.6 g of ammonium polyacrylate were dissolved in 30 mL of deionized water. After complete dissolution, they were added to mixture I, and the mixture was stirred continuously to obtain mixture II.

[0084] Mixture II was poured into a reaction vessel with a polytetrafluoroethylene substrate and hydrothermally treated at a constant temperature of 180°C for 36 hours, then aged at room temperature for 6 hours to obtain a solid product. The solid product was filtered, washed repeatedly with deionized water and ethanol, dried under vacuum at 70°C for 24 hours, and then calcined at 500°C for 16 hours to obtain the catalyst.

[0085] Example 2

[0086] Ferric nitrate nonahydrate (Fe(NO3)3·9H2O) containing 0.1 mol Fe, copper nitrate trihydrate (Cu(NO3)2·3H2O) containing 0.03 mol Cu, strontium nitrate (Sr(NO3)2) containing 0.02 mol Sr, and samarium nitrate hexahydrate (Sm(NO3)2·6H2O) containing 0.015 mol Sm were sequentially dissolved in 100 mL of deionized water. After complete dissolution, mixture I was obtained. 5.2 g of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (P123) and 1.5 g of ammonium polyacrylate were dissolved in 30 mL of deionized water. After complete dissolution, they were added to mixture I, and the mixture was stirred continuously to obtain mixture II.

[0087] Mixture II was poured into a reaction vessel with a polytetrafluoroethylene substrate and hydrothermally treated at a constant temperature of 160°C for 40 hours, then aged at room temperature for 5 hours to obtain a solid product. The solid product was filtered, washed repeatedly with deionized water and ethanol, dried under vacuum at 70°C for 20 hours, and then calcined at 520°C for 12 hours to obtain the catalyst.

[0088] Example 3

[0089] Ferric nitrate nonahydrate (Fe(NO3)3·9H2O) containing 0.1 mol Fe, copper nitrate trihydrate (Cu(NO3)2·3H2O) containing 0.04 mol Cu, barium nitrate (Ba(NO3)2) containing 0.025 mol Ba, and lanthanum nitrate (La(NO3)3) containing 0.01 mol La were sequentially dissolved in 100 mL of deionized water. After complete dissolution, mixture I was obtained. 4.8 g of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (P123) and 1.6 g of ammonium polyacrylate were dissolved in 30 mL of deionized water. After complete dissolution, the dissolved components were added to mixture I, and the mixture was stirred continuously to obtain mixture II.

[0090] Under the same conditions as in Example 1, a catalyst was obtained.

[0091] Example 4

[0092] The catalyst was prepared according to the method of Example 1, except that the structure modifier was changed to 7.6 g of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer (P123), and other conditions were the same as in Example 1.

[0093] Example 5

[0094] The catalyst was prepared according to the method of Example 1, except that the hydrothermal treatment conditions were: hydrothermal treatment at 250°C for 15 hours, and other conditions were the same as in Example 1.

[0095] Comparative Example 1

[0096] The method is the same as in Example 1, except that the contents of Fe source, A source, M source, and Q source in mixture I are changed, specifically:

[0097] Ferric nitrate nonahydrate (Fe(NO3)3·9H2O) containing 0.1 mol Fe, copper nitrate trihydrate (Cu(NO3)2·3H2O) containing 0.15 mol Cu, magnesium nitrate hexahydrate (Mg(NO3)2·6H2O) containing 0.4 mol Mg, and neodymium nitrate hexahydrate (Nd(NO3)3·6H2O) containing 0.2 mol Nd were sequentially dissolved in 100 mL of deionized water. After complete dissolution, mixture I was obtained. Other conditions were the same as in Example 1 to prepare the catalyst.

[0098] Example 6

[0099] Mixture I was prepared according to the method in Example 1, except that 28 wt% ammonia solution (molecular formula: NH3·H2O) was added to mixture I, the pH was maintained at 9.0, and after continuous stirring, it was aged at room temperature for 6 hours to obtain mixture II. Mixture II was filtered, washed repeatedly with deionized water and ethanol, dried under vacuum at 70°C, and then calcined at 500°C for 16 hours to obtain the catalyst.

[0100] Test case

[0101] To evaluate the catalytic performance of the catalyst, in Syngas conversion reaction was carried out in a millimeter fixed-bed reactor. The composition, particle size and evaluation results of the catalyst are listed in Table 1.

[0102] Reduction conditions: reduction temperature 470℃, reducing agent hydrogen, reduction pressure atmospheric pressure, catalyst loading 4 mL, and reducing agent volume hourly space velocity 6500 h⁻¹. -1 The restoration time is 40 hours.

[0103] Reaction conditions: reaction temperature 370℃, reaction pressure 1.3MPa, catalyst loading 4mL, catalyst loading 5500h. -1 The raw material ratio (moles) H2 / CO = 2.5 / 1.

[0104] Table 1

[0105]

[0106] As can be seen from the results in Table 1, the reaction of syngas conversion to low-carbon olefins using the iron-based catalyst of the present invention has a higher CO conversion rate and a higher selectivity for low-carbon olefins.

[0107] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. An iron-based catalyst characterized in that, The catalyst has a structure shown in the following formula: FeA a M b Q c O x ; wherein A is Cu; M is at least one selected from Mg, Sr and Ba; Q is at least one selected from Nd, Sm and La; a, b and c are molar ratios of A, M and Q to Fe respectively, a = 0.1-0.6; b = 0.1-0.4; c = 0.05-0.2; x is the total number of oxygen atoms required to satisfy the valence of each element in the active component; The particle size of the catalyst is 200-900 nm.

2. The catalyst of claim 1, wherein, a=0.2-0.5。 3. The catalyst of claim 1, wherein, M is Mg and / or Sr; And / or, b = 0.1-0.

35.

4. The catalyst of claim 1, wherein, Q is Nd and / or Sm; And / or, c = 0.05-0.

15.

5. The catalyst of claim 1, wherein, The particle size of the catalyst is 250-500 nm.

6. A process for the preparation of the iron-based catalyst according to any one of claims 1 to 5, characterized in that, The method comprises: (1) preparing a mixed solution comprising a source of Fe, a source of A, a source of M, a source of Q and a structure regulator; (2) subjecting the mixed solution to hydrothermal treatment, drying and calcining the obtained solid product to obtain the iron-based catalyst.

7. The production method according to claim 6, wherein The source of Fe is at least one selected from ferric nitrate, ferric chloride and ferric sulfate; And / or, the source of A, the source of M and the source of Q are each independently nitrate and / or chloride.

8. The production method according to claim 6, wherein The structure regulator is a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer and / or ammonium polyacrylate.

9. The production method according to claim 8, wherein The structure regulator is a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer and ammonium polyacrylate.

10. The production method according to claim 9, wherein The mass ratio of the polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer to ammonium polyacrylate is 0.5-5:

1.

11. The production method according to claim 10, wherein The mass ratio of the polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer to ammonium polyacrylate is 1-4:

1.

12. The method of making according to claim 6, wherein, The amount of the structure regulator added is 30-60 wt% of the total weight of the catalyst prepared.

13. The method of making according to claim 12, wherein, The amount of the structure regulator added is 35-55 wt% of the total weight of the catalyst prepared.

14. The production method according to claim 6, wherein, The conditions of the hydrothermal treatment include: a reaction temperature of 120-260℃; and a reaction time of 12-60 hours.

15. The method of making according to claim 14, wherein, The conditions of the hydrothermal treatment include: a reaction temperature of 140-240℃; and a reaction time of 18-54 hours.

16. The method of making according to claim 6, wherein, The calcination conditions include: a calcination temperature of 400-600℃; and a calcination time of 3-36 hours.

17. The method of making according to claim 16, wherein, The calcination conditions include: a calcination temperature of 450-550℃; and a calcination time of 6-30 hours.

18. Use of the iron-based catalyst of any one of claims 1-5 in the synthesis of syngas into low-carbon olefins.

19. Use according to claim 18, wherein, The conditions for the synthesis gas conversion reaction include: the synthesis gas includes CO and H2; the reaction temperature is 280-400°C; the reaction pressure is normal pressure-8 MPa; the H2 / CO molar ratio is 1-5:1; the catalyst loading is 500-12000 h -1 .

Images